The present invention concerns an interior luminaire, in particular for the illumination of merchandise display surfaces, having a transparent luminaire shade and an optical system with a light-emitting means.
Merchandise display surfaces, for example refrigerator cases, fruit bins, retail shelves, etc., are usually artificially illuminated. The goal is to illuminate the surfaces as homogeneously as possible. Interior luminaires of the kind cited above having transparent luminaire shades are used, for example, for this purpose. These conventional interior luminaires have the disadvantage that they generate a dazzle effect, since the light-emitting means is visible externally as a particularly bright point or surface. The interior luminaires moreover possess only a small degree of light deflection, with the result that only a small portion of the lamp""s luminous flux actually strikes the usable area that is to be illuminated. In addition, vertical light-emitting means and rotationally symmetrical reflectors, which each generate a circular illuminating surface, are often used in such interior luminaires. This results in the disadvantage that high peak illumination intensities are produced at the center of the circle, with the result that the merchandise items can become faded and bleached; and moreover, with wide light distributions, a large portion of the circular light cone falls not on the sales fixture but into the customer and service area. The result is poor efficiency in terms of usable illumination.
Luminaires having a horizontal light-emitting means, which generate oval illuminating surfaces, are therefore alternatively used. These luminaires having a horizontal light-emitting means do represent an improvement for the illumination of elongated display surfaces, but the luminaire shade is still inhomogeneously illuminated.
It is therefore the object of the invention to configure an interior luminaire of the kind cited initially in such a way that the luminaire shade is homogeneously illuminated and, in particular, that dazzle effects are eliminated.
This object is achieved, according to the present invention, in that the optical system is positioned in a light-emitting means space provided above the luminaire shade and radiates light into the luminaire shade through a light entry opening on the upper side thereof, and that an inwardly projecting, diffusely reflecting flange, which reflects at least a portion of the emerging light back into the luminaire shade, is provided at the lower rim of the luminaire shade.
With the known interior luminaires the problem existed, as already described, that the light-emitting means was clearly visible to an observer through the transparent shade as a bright area. According to the present invention this is now avoided by the fact that the light-emitting means is housed outside the lamp shade in the light-emitting means space, with the consequence that a homogeneous illumination of the lamp shade is achieved.
This effect is even further reinforced by the fact that at the flange which is provided at the light exit opening of the lamp shade, a portion of the emerging light is reflected back into the lamp shade, i.e. additionally brightens it.
According to a further embodiment of the invention, the luminaire shade is made of light-transmissive material, for example an acrylic material, that has total-reflection properties as a result of its surface structure. Homogeneous illumination of the lamp shade is further assisted by this surface structure.
In order to optimize homogeneous illumination of the luminaire shade, the latter can furthermore be configured and mounted in a light-emitting means space in such a way that a portion of the light radiated by the optical system enters directly into the material of the luminaire shade.
According to a further embodiment, provision is made for the light-emitting means to be a high-pressure discharge lamp in a horizontal operating position. The use of such high-pressure discharge lamps makes possible the concentrated generation of high light fluxes, and thus high power conversion in a small space. The use of such light-emitting means in a horizontal operating position, optionally in combination with corresponding reflectors that generate, for example, a bat-wing light intensity distribution, furthermore allows elongated areas to be illuminated homogeneously, so that the number of luminaires necessary for illumination of a long display area can be minimized.
The ballast units necessary when high-pressure discharge lamps of this kind are used can be provided, for example, in an operating equipment space, provided adjacent to the light-emitting means space and in particular above the latter, that is thermally insulated from the light-emitting means space so that the ballast units are not negatively is affected by the heat evolved by the light-emitting means during operation. For example, heat shields can be provided between the light-emitting means space and the operating equipment space.
In addition, the flange at the lower rim of the luminaire shield can be partially light-transmissive and can diffusely scatter the light that passes through. For example, the flange as well as the lamp shade can be made of an acrylic material.
Lastly, the flange can be selectively reflective in order to filter out specific color components. In the same fashion, the light entry opening of the luminaire shade can have in front of it a filter that filters specific color components out of the light emitted by the light-emitting means, in order to emphasize complementary colors.